1. Field of the Invention
This invention relates generally to systems and methods for cooling rack-mounted assemblages of individual electronic units, and more particularly to air to water heat exchangers in rack-mounted computer server units.
2. Description of the Related Art
Computing and telecommunications devices, such as routers, switches, network servers, and other similar types of devices, are often mounted in racks that are housed in medium or large size enclosures or cabinets. The use of enclosures and cabinets to house the computing and telecommunication devices concentrates the electronic equipment to better utilize space. However, the power dissipation and the resultant generation of heat by integrated circuit chips, and the modules containing the chips, continues to increase with increases in processor performance. The concentrations of modules in racks housed in enclosures and cabinets leads to heat building up around the modules. Integrated circuit chips, microprocessors, and other similar electronic components are designed to operate within a particular temperature window. Accordingly, the heat generated by such components must be removed from the enclosure they are housed in or else the components will overheat and fail.
Many cooling arrangements for electronic cabinets and enclosures are well known including the use of forced air from fans to remove heat, air to air heat exchangers, and air to water heat exchangers. In an effort to reduce server heat emissions, International Business Machines Corporation has introduced a rear door air to water heat exchanger that utilizes existing chilled water supplies from air conditioning systems that are normally already located in datacenters. Air to water heat exchangers ease the burden on existing air conditioning units within a datacenter, which are often already running at full capacity. The use of an air to water heat exchanger eases the burden on air conditioning systems by transferring some of the accumulated heat with an enclosure to the re-circulating water instead of to the ambient air.
FIGS. 1, 3, and 6 illustrate an existing rear door air to water heat exchanger and related fluid or water supply system. FIG. 1 illustrates a rear door 100 with fins 102 behind a protective barrier 104. The fins 102 conduct or transfer ambient heat to coils (hidden from view) that carry cooling fluid or water. The cooling fluid or water is supplied via a female coupling 106 and supply manifold 108. Cooling fluid or water that has been heated by the transferred ambient heat exits the rear door 100 via the return manifold 110 and male coupling 112. Female coupling 106 and male coupling 112 are joined with quick connects to flexible supply 122 and return hoses 124, respectively, of FIG. 3. The flexible supply 122 and return hoses 124 are held in place by hose retention plate 114. Drain port 116 provides a path for accumulated condensation. Air-purging valve 118 for the supply manifold 108, and air-purging valve 120 for the return manifold 110 remove air from the coils (hidden from view) that may affect the ability of the coils to remove heat from the rear door 100.
FIG. 6 is a schematic diagram of an existing air to water heat exchanger system 600. The example system 600 is shown with three rear doors 602, 604, and 606 of enclosures 608, 610, and 612, respectively. Chilled water from a building's air conditioning system is passed through a water to water heat exchanger 630 to cool down (draw away heat from) water or fluids that are supplied to the rear doors (602, 604, 606) via pump 614 and overflow tank 628 and input distribution manifold 616. Heated water from the rear doors (602, 604, 606) is returned via return distribution manifold 618. The distribution manifolds (616, 618) are equipped with quick disconnects 620 for connecting flexible supply and return hoses (shown in greater detail in FIGS. 1, 3, and 5). Flow control valve 622 receives specifications (signified by the letter S) from a central controller 626. A temperature sensor 624 provides feedback (signified by dotted line) to the flow control valve 622 about the temperature of the water or fluids being returned from the rear doors (602, 604, 606). The temperature feedback is compared to the specification range, and the flow control valve is adjusted accordingly. For example, if the temperature in the return line is increasing, the flow rate of the chilled water is increased in order to decrease the temperature of the water or fluids being sent to the rear doors (602, 604, 606).